This is the least interesting of the bunch, being a well-documented board in the wiki : wiki/Cherry_G81-0991, so I won't comment most of the pictures.
This is where things start to get interesting, I bought this keyboard thinking it might have unique article number (considering we had only ever see those Goupil "1000" keyboads with Cherry MY switches). But to my surprise, opening it up and checking for the label revealed it was ... still a "0991HAF", this is where the conspiracy part of my brain got fired up. It doesn't explicitly mentions "G80", nor did the previous "G81"-0991HAF, only "0991HAF". Even makers of the wiki page assumed it was a G81 because it so obviously should be, but it's only with later models (a B50 G81-0991HDF, a C03 G81-1236HCR and a B39 G81-1236HBR) that we get a complete article code.
Definitely the Cherry MX Blacks we've all came to love through the years
This was a VERY unexpected find, to say the least, a friend was touring shops for furnitures when he stumbled upon a vaguely mechanical keyboard, asking if it was of any interest to me. Which of course I freaked out! what are the chances of finding a Goupil board 10km away just rotting away on a table of some shop ?! Of course I had to try to trade it for some kind of keyboard I had and decided an Acer 6312 was bad good enough as a replacement for anyone, plus they were getting a working keyboard! I was the one losing in this trade! And so the trade happened.
Had to take a picture of it in its very real work office, a find too good to be true
So ? Why so much extrapolating ?
Well, I take the documentation work I and others are doing very seriously, and so lazily documenting might not end up in any advancement in the understanding of the mind that is the Cherry article code and number scheme.
What I get from these finds is that Cherry doesn't use the article code as an identifier, but more as a descriptive. The 0991HAF code that can both denominate a G80 or a G81 is confusing, but I imagine 0991 is just a description of what this keyboard is, in its most simple description, a Y keyboard, with an X case, and a Z number of keys. Though ... and this is another conspiracy kind of thing, but this might have been the keyboard that lead Cherry to make the G81 line. We've not found all of the <991 keyboards, but there is at least one exemple of a G80 coming with MX : https://imgur.com/a/Uxz0uWy. Which implies that before the "G81" came to be, Cherry MY was treated as any other switch and the keyboard they were in, as any other G80.
The questions are ...
Is this the keyboard that lead Cherry to make the G81 line ?
Should we assume
When is actually the first "G81" ?
Does it precede the "G81"-0991HAFs we have seen ?
Does the G81-1103H supercede the first G81 ?
But being immensely bored and very interested in the subject, I took a small sample size of the boards we have in the database :
The G81-1000HAI is weird but I included it for the sake of being strict
... and my answers are
Is it THE keyboard ? ... I don't know, I would have more firmly said yes if the dates made sense, as in, both 0991HAF predated the other G81s, and they don't. But at the same time, the argument that the 1109HAD in this sample was a "special" board as well makes sense. I mean, imagine the (G80-)0991HAF being a bit older, and all of the sudden it makes sense that before the 22nd week of 1988, all boards with Cherry MY but the G81-1000 were G80s. Or even a bit more bold, take out the 1000HAI as a bad sample, and the G81 line was born between the 22nd and 26th week of 1988 ... ? and no, I don't think we should default to G81 when a Cherry board with MY switches appears and doesn't explicitly says so.